Vernon L Mcnabb

US Patent:

40561259, Nov 1, 1977

Filed:

Oct 2, 1975

Appl. No.:

5/618976

Inventors:

Vernon L. McNabb - Van Nuys CA

Assignee:

The Bendix Corporation - North Hollywood CA

International Classification:

F16K 4708
F16B 1304

US Classification:

1376253

Abstract:

Multiple path means for a fluid flow control device is shown in connection with a typical spool type servo valve wherein the spool member moves within a stationary sleeve to control fluid flow to a piston in a cylinder. The multiple path means includes a series of stacks of washer-like elements or disks which are positioned in radial bores in the valve sleeve and which disks cooperate when the spool number moves a small distance from null to define a restricted path across the stack in which flow is forced through a series of alternating chambers and orifices with measured pressure drops across the orifices. Further movement of the spool member away from null opens a large parallel flow path. Since many servo valves have comparatively short travel and since both control and wear problems of such valves tend to be most serious near null, the restricted flow path is utilized to minimize abrupt step flow gains with the usual accompanying wear around null.